Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
2021 Subaru Ascent BaseFACTORY OEM SERVICE PROCEDURE
Tire Pressure Monitoring System DTCS
TIRE PRESSURE MONITORING SYSTEM DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION
| Code | Reference |
|---|---|
| C2021 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2021 FL TIRE AIR PRESSURE DECREASE NORMAL MODE . |
| C2022 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2022 FR TIRE AIR PRESSURE DECREASE NORMAL MODE . |
| C2023 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2023 RR TIRE AIR PRESSURE DECREASE NORMAL MODE . |
| C2024 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2024 RL TIRE AIR PRESSURE DECREASE NORMAL MODE . |
| C2121 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2121 FL TRANSMITTER NO DATA . |
| C2122 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2122 FR TRANSMITTER NO DATA . |
| C2123 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2123 RR TRANSMITTER NO DATA . |
| C2124 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2124 RL TRANSMITTER NO DATA . |
| C2221 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2221 FL TRANSMITTER PRESSURE DATA ABNORMAL . |
| C2222 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2222 FR TRANSMITTER PRESSURE DATA ABNORMAL . |
| C2223 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2223 RR TRANSMITTER PRESSURE DATA ABNORMAL . |
| C2224 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2224 RL TRANSMITTER PRESSURE DATA ABNORMAL . |
| C2321 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2321 FL TRANSMITTER STATUS ABNORMAL . |
| C2322 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2322 FR TRANSMITTER STATUS ABNORMAL . |
| C2323 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2323 RR TRANSMITTER STATUS ABNORMAL . |
| C2324 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2324 RL TRANSMITTER STATUS ABNORMAL . |
| C2421 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2421 FL TRANSMITTER BATTERY VOLTAGE DECREASE . |
| C2422 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2422 FR TRANSMITTER BATTERY VOLTAGE DECREASE . |
| C2423 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2423 RR TRANSMITTER BATTERY VOLTAGE DECREASE . |
| C2424 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2424 RL TRANSMITTER BATTERY VOLTAGE DECREASE . |
| C2521 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2521 SPEED ABNORMAL . |
| C2721 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2721 THRESHOLD READ MALFUNCTION . |
| C2821 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2821 WHEEL POSITION SENSING ABNORMAL . |
| C2921 | Ref. to TIRE PRESSURE MONITOR (DIAGNOSTICS)>Diagnostic Procedure with Diagnostic Trouble Code (DTC)>DTC C2921 ID REGISTRATION ERROR . |
Factory Service Tools
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.